One strange thing was that both Carradine and Sondegard in this movie looked like they were past their prime, which is strange because this was the mid 40s and I know neither of them were yet.
The invisible man has the final movie of their series about a guy who goes back to the basics of what made invisible man partly so great in the first place, a paranoid ambition to correct all of the wrongs that were made against him. Not since the first movie was an invisible man this bad.
He thinks he has been betrayed by his family so after some help from a scientist played by John Carradine he has his revenge against them as the invisible man. This includes murder of a couple different people including Carradine and once he gets his come uppance from the dog that belonged to Carradine we feel that it is very richly deserved.
It’s nice to see the invisible man as an actual villain again after spending so much time as somebody who was misunderstood or serving his country. The creatures will always be part villain to us and that is why we appreciate them.